#' Index of Countries.
#'
#' Data frame containing a normalized index of countries.\cr
#' Data are used by \code{\link{biblioAnalysis}} function
#' to extract Country Field of Cited References and Authors.
#'
#' @format A data frame with 199 rows and 5 variables:
#'  \describe{
#'     \item{countries}{country names}
#'     \item{continent}{continent names}
#'     \item{iso2}{country ISO 3166-1 alpha-2 code}
#'     \item{Longitude}{country centroid longitude}
#'     \item{Latitude}{country centroid latitude}
#'     }
#'
#' @name countries
NULL
